Emojis have emerged as prominent visual-paralinguistic cues in computer-mediated communication, yet empirical evidence on their persuasive role in digital advertising remains limited. This study investigates how the presence of emojis in social media advertisements influences consumers’ positive affect and purchase intention, and whether these effects vary across hedonic and utilitarian product framings. Drawing on affect-based persuasion and textual paralanguage theories, a 2 (emoji presence: present vs absent) × 2 (product framing: hedonic vs utilitarian) between-subjects experimental design was employed. Data were collected from 217 participants who were exposed to simulated YouTube advertisements and analysed using analysis of variance and mediation analysis. The results reveal that advertisements containing emojis generate significantly higher levels of positive affect and purchase intention than those without emojis. Mediation analysis further demonstrates that positive affect fully mediates the relationship between emoji presence and purchase intention, underscoring the central role of emotional mechanisms in emoji-based persuasion. Contrary to prior assumptions, product framing does not moderate these effects, indicating that emojis exert a robust persuasive influence across both hedonic and utilitarian advertising contexts. By providing causal evidence from a controlled experimental setting, this study extends emoji research from interpersonal communication to persuasive digital marketing contexts and highlights emojis as low-cost yet effective tools for enhancing emotional engagement and consumer response in social media advertising.